Adding a Windows 2000 network drive to a Windows 7 machine

In this case, it was also on a workgroup. It will not accept the password because of the authenticated method that changed in W7.

You have to go into the registry to
HKLM\SYSTEM\CurrentControlSet\Control\Lsa
and then ADD a DWORD value of LmCompatibilityLevel and set it to 1 (one)

No reboots required, it worked immediately for me. Since it was on a workgroup the credentials were server\administrator and then the password, and I had to check the box to run with different credentials.